upgrading the liquid-fueled heating appliance while
increasing the amount of biodiesel/renewable liquid
fuel used by that appliance.
The calculator uses an Excel-based spreadsheet that
allows the user to make key input changes to examine
the results of different actions and approaches to
reduce greenhouse gases. It also shows how macro
activities in the background, such as the decarbonization
of the electrical grid, impact the results. Additional
factors may be added, either in conjunction
with NORA or independently. Like most models, this
was developed over time with input from many stakeholders.
Good modeling practice has been the basis for
this open source Excel Calculator. To ensure the accuracy,
the model was reviewed by EarthShift Global
CEO & Founder Lise Laurin. Version 7.1 was deemed
to “fairly and accurately present the impact of changes
in variables.”
Connecticut use-case
To explain the GHG Calculator and its functions, along
with the impact of different variables, this article will
use a variety of inputs focused on a Connecticut usecase.
Figure 1 provides the result for the Connecticut
use-case and shows the effects of converting all current
oil-heated homes to no-carbon liquid solutions
by 2050. This model uses normal 5% liquid fuel appliance
upgrades per year versus all-electric (heat pump
plus resistance backup) conversions at a rate of 1% per
year. This graphic shows how the high use of biodiesel
blending, along with normal appliance upgrades,
reduce carbon emission considerably faster and at a
much lower cost than does converting to electric heat
pumps.
Connecticut has a biodiesel use mandate in place and
its effect on carbon emissions can be seen by the lighter
green color in Figure 1. In fact, the mandated levels
produce carbon reductions more than three times
greater than will heat pumps (orange). Additionally,
if an ever-higher biodiesel blend scenario is implemented
(darker green), the GHG savings are almost
five times as great by 2050.
Of equal importance, the reduction using biodiesel
comes at a much smaller cost. Using 2030 as a snapshot,
the GHG reduction cost with heat pumps is more
than three times greater than with the biodiesel.
Calculator inputs
To ensure accuracy and flexibility, the GHG Calculator
allows for more than 30 different inputs (Table
1). Among these are: location, global warming atmospheric
lifetime, biodiesel feedstock, heating appliance
efficiency, heat pump performance, heating load,
biodiesel uptake scenarios, grid decarbonization rates
and liquid fuel appliance and heat pump installation
rates. The calculator allows additional inputs that include
costs for both fuels and installation and conversion
costs.
Using the GREET Model, the calculator assigns
carbon emissions weight from both the liquid fuels
and electricity. GREET stands for Greenhouse Gases,
Regulated Emissions & Energy use in Technologies;
Table 1: GHG Calculator Variable Input Table
City for Weather Data to be Applied to the Homes: Hartford, CT
Global Warming Atmospheric Lifetime: 100 Year Lifetime-AR5
Biodiesel Feedstock: Average of Bioblend
Feedstocks
Average Liquid Fueled Baseline Efficiency: 78%
Liquid Fueled Non-Condensing Boiler Efficiency: 86%
Liquid Fueled Boiler Retrofits: 5.00%
Select Liquid Fueled Thermal Heat Pump Retrofits: 5.00%
Electric Heat Pump (EHP) Performance Curve: HP7
Electric Resistance Seasonal
Performance Efficiency: 100%
Annual Home Heating Load MMBtu/year: 100
Bioblend Uptake Scenario:
Scenario 2:
B5 in 2023, B20 in 2025,
B50 in 2030, B100 in 2040
Decarbonization rate over 2021 Baseline for
Marginal Electricity and Biofuels:
Scenario 3:
15% in 2025, 25% in 2030,
50% in 2040 & 100% in 2050
Homes to be Assessed
(If State Selected, it must agree with City Selected): Connecticut
Whole Home Heating Electrification Rate:
(HP + electric BU Heating) 535,420
Whole Home Heating Electrification Rate:
(HP + electric BU Heating) 5.00%
Annual Heating Electrification Conversions: 26,771
Heat Pump Conversion Cost Estimation Curve: Low Conversion Cost
Scenario 2
Percentage of Load Served by Heat Pump: 100.0%
Average Conversion Cost of One Whole House
Heat Pump with Electric Backup: $25,000
Select Discount Rate for Heat Pump
Program Cost Calculation: 2.00%
Diesel Cost per MMBtu $22.71
Biodiesel Cost per MMBtu $26.56
EL Cost per MMBtu $30.00
Cost of Electricity 2020 EIA Connecticut ¢/kWh $0.23
Cost of Electricity 2020 EIA Connecticut $/MMBtu $66.6
Low Replacement Cost Non-Condensing Boiler $5,500
High Replacement Cost Non-Condensing Boiler $9,500
Low Replacement Cost Condensing Boiler $10,000
High Replacement Cost Condensing Boiler $15,000
Low Replacement Cost Thermal Heat Pump $12,000
High Replacement Cost Thermal Heat Pump $17,000
The GHG Calculator allows for more than 30 variable inputs.
This table shows the inputs selected for the Connecticut use-case model.
ICM/November/December 2022 5